The present invention generally relates to heat exchanger assemblies of the type used in an aircraft environmental control system ("ECS"). Such heat exchangers are usually of the fluid-to-fluid type, either gas or liquid, and typically have a core assembly including alternating rows of heat transfer fins and plates. The rows are interposed to create multiple, hot and cold side passageways extending through the core assembly. The passageways may create a counter-flow, parallel flow or cross-flow heat exchange relationship between fluids flowing through the passageways. During operation, heat is exchanged between the fluids flowing through the core assembly.
Because an aircraft ECS often operates at, and generates within itself, extreme temperature and pressure conditions, the heat exchanger is subjected to the adverse effects of temperatures as well as the forces generated by operation of the aircraft. The heat exchanger is manufactured to function in such a hostile environment. Fin-plate type heat exchangers typically include a core and inlet and outlet manifolds. The core typically includes rows of fin assemblies and support plates that support as well as separate adjacent rows of fin assemblies. Each fin assembly is usually formed from one or more corrugated sheets and at least two fluid enclosure bars, which are bonded, typically by brazing, to a pair of support plates. After the components are assembled to form the core, the core is welded to the inlet and outlet manifolds. In order to build up a surface of solid material upon which to weld the manifolds, a butterpass weldment is first placed on the edges of the core.
When heat exchanger cores are subjected to the butterpass and/or general manifold weldment procedures, they may suffer certain drawbacks that increase the manufacturing costs and reduce the overall quality of the resulting heat exchanger. If the core is welded to the manifold, the size (i.e., gage) of the core material receiving the weld may be thicker than would otherwise be needed in order to support the weldment. This additional amount of core material can significantly increase the overall weight of the core assembly. Consequently, the weight of the aircraft is increased which, in turn, increases fuel consumption and increases aircraft operating costs.
If a conventional butterpass or similar weld is used to secure the heat exchanger components, and if there are initial stresses or flaws in the welds, some of the welds may fail. Consequently, the life cycle of the heat exchanger will be reduced.
There currently exists a need for a heat exchanger assembly that overcomes the drawbacks associated with welding the manifolds to the core.